Temporal differences in mating behavior between rice- and water-oats-populations of the striped stem borer, Chilo suppressalis (Walker) (Lepidoptera: Crambidae)

Abstract

Rice-feeding and water-oats-feeding populations of Chilo suppressalis usually occur over areas around paddy fields in Japan. Laboratory observations showed temporal differences in mating and female calling between the populations. The rice-population was sexually active in the first half of the scotophase whereas the water-oats-population was sexually active in the second half of the scotophase. Under a no-choice condition in the laboratory, adults of the rice- and water-oats-populations could hybridize in both reciprocal crosses. However, mating frequency was significantly lower in crossings between females of the rice-population and males of the water-oats-population than in the opposite crosses. The peak time of mating in the F1 generation was intermediate between the times of their parental populations. Similar patterns of mating time were observed in the F2 generation. These results indicate that the time of mating in C. suppressalis is genetically controlled, most likely by a polygenic system.